Exhausts?

[Benjibrady]

Quick question,

After reading that exhaust systems differ between n/a and force inducted engine set ups from what I gather with forced induction you want maximum flow and no back pressure. By that theory why are we not following 'bigger is better' and driving around with 3" or 4" systems?

[Trevhib]

Isn't at least some back pressure required? I forget now. Was one of the reasons something to do with oil seals in the turbo? My memory is shocking.

[Haz]

Bigger is better, but depends on the amount of air passing through it all, more so how restrictive it is. Turbo systems can be bigger but 2.5" is good enough for over 250bhp.
More to the point though, try and fit 3" from turbo to back of the car ;)

[Benjibrady]

Yeah I can imagine trying to get that much scaffolding pole underneath can be a bit of a challenge I was just speak hypothetically. Could flow be reduced with a larger bore?

[DaveL485]

NA cars want a measured diameter as cylinder scavenging has more relevance, and modifying the exhaust gas velocity by changing exhaust tube diameters will have a bigger impact. Its part of maintaining a linear acceleration curve of the air right through the engine IIRC.

In Turbo cars it doesnt matter as much, so the bigger the better, partly I think due to the exhaust having a whopping great turbine in the way :D
However, why would you have a 4" when it has no benefit over a 2.5" as your performance is limited by the rest of the engine?


Scoff will be along shortly to outgeek us all, i'm sure :agree: